During the last half decade, hundreds of scientists from many countries have been studying the samples, photographs, and instrumental data returned from the moon by the Apollo and Luna programs. These studies have placed significant limits on chemical, petrologic, and physical parameters, on the time of many events, and on the rate of many processes and are giving greater insight into the natural processes that formed the moon and shaped its surface. Increasingly, it is being recognized that very similar processes governed the origin and evolution of planetary bodies throughout the solar system. Spacecraft have extended our sensors to all the terrestrial planets, and the insights gained from Apollo dominate our interpretation of the photographic and instrumental data returned from these bodies.A major accomplishment of the Apollo and Luna programs is the transformation of planetary science from a discipline with important but untestable ideas to one in which the questions are both important and testable. Measurements on returned lunar samples, surface observations by astronauts, data from orbital and surface instruments, and orbital photographs have settled generations old controversies, which were stimulated by the extreme positions taken by men with equally great scientific intuition and eloquence but few facts. Some earlier speculations have been contradicted and are now forgotten, while others have been made to look like axiomatic truths. Almost forgotten now is the intensity of the controversy on such subjects as the 'cold old Copyright ¸ 1975 by the American Geophysical Union. moon' versus the 'hot young moon,' the depth to which a spacecraft might sink into uncompacted dust, the volcanic origin of craters and mare, the importance of water in shaping the mare and producing other topographic features, whether accumulated radiation would be released explosively as the astronaut touched the lunar surface, the presumption of a constant cratering rate throughout lunar history, the possibility of exotic lifeforms at depth in the drill cores even when none had been found in surface samples, the assertions that the dark color of certain lunar mountains is due to the abundance of carbon and that tectites come from the moon, etc. The answers may now seem obvious to the young scientists of today, but such controversies consumed countless manhours and thousands of printed pages during Apollo planning.The flood of published lunar research has inundated even those scientists actively involved in lunar studies. In this review article, neither an attempt at a comprehensive listing of the papers nor a highly condensed survey of the research seems useful. A number of comprehensive papers have appeared recently which collectively provide both an excellent synthesis of lunar science and a good entree into the important literature. Hence this article will review a selected group of these papers.Four of the selected papers can be combined to provide a comprehensive and generally acceptable model for the formation and evolution ...
